U.S. patent number 7,553,548 [Application Number 10/565,940] was granted by the patent office on 2009-06-30 for laminated sheet for molding.
This patent grant is currently assigned to Dainippon Ink & Chemicals, Inc.. Invention is credited to Masanobu Fukuda, Tatsuya Kouyama, Kouji Shiota, Kenkichi Yano.
United States Patent |
7,553,548 |
Fukuda , et al. |
June 30, 2009 |
Laminated sheet for molding
Abstract
A laminated sheet for molding comprising: a film layer which
comprises thermoplastic acrylic resin, wherein the film layer is
one of transparent or translucent; an intermediate layer which
comprises a curable resin including a polyisocyanate compound and
an acrylic resin having hydroxyl groups, wherein the a curable
resin is a cured material in a semi-cured state; and a decorative
layer having a mirror-like metallic luster, which comprises a
binder resin and fine metal grains obtained from a thin metal film;
wherein the layers are laminated in the order stated.
Inventors: |
Fukuda; Masanobu (Okegawa,
JP), Shiota; Kouji (Tokyo, JP), Kouyama;
Tatsuya (Toda, JP), Yano; Kenkichi (Tokyo,
JP) |
Assignee: |
Dainippon Ink & Chemicals,
Inc. (Tokyo, JP)
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Family
ID: |
34113623 |
Appl.
No.: |
10/565,940 |
Filed: |
July 27, 2004 |
PCT
Filed: |
July 27, 2004 |
PCT No.: |
PCT/JP2004/011034 |
371(c)(1),(2),(4) Date: |
January 26, 2006 |
PCT
Pub. No.: |
WO2005/011977 |
PCT
Pub. Date: |
February 10, 2005 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20060240246 A1 |
Oct 26, 2006 |
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Foreign Application Priority Data
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Jul 30, 2003 [JP] |
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2003-203698 |
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Current U.S.
Class: |
428/515; 427/331;
427/372.2; 428/220; 428/323; 428/332 |
Current CPC
Class: |
B44C
1/14 (20130101); B32B 7/10 (20130101); B32B
7/12 (20130101); B32B 27/08 (20130101); B32B
27/18 (20130101); B32B 27/30 (20130101); B32B
27/308 (20130101); B32B 27/40 (20130101); B32B
2509/00 (20130101); B32B 2551/08 (20130101); B32B
2605/00 (20130101); B32B 2255/10 (20130101); B32B
2255/205 (20130101); B32B 2255/26 (20130101); B32B
2255/28 (20130101); B32B 2264/0228 (20130101); B32B
2264/025 (20130101); B32B 2264/0257 (20130101); B32B
2264/105 (20130101); B32B 2264/12 (20130101); B32B
2307/306 (20130101); B32B 2307/406 (20130101); B32B
2307/412 (20130101); B32B 2307/414 (20130101); B32B
2307/416 (20130101); B32B 2419/00 (20130101); Y10T
428/31909 (20150401); Y10T 428/31935 (20150401); Y10T
428/269 (20150115); Y10T 428/256 (20150115); Y10T
428/25 (20150115); Y10T 428/26 (20150115); Y10T
428/265 (20150115) |
Current International
Class: |
B32B
5/16 (20060101); B05D 1/40 (20060101); B05D
3/02 (20060101); B32B 27/08 (20060101); B32B
27/32 (20060101) |
Foreign Patent Documents
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05-111991 |
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May 1993 |
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JP |
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2002-046230 |
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Feb 2002 |
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JP |
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2002-187238 |
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Jul 2002 |
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JP |
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2003-136636 |
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May 2003 |
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JP |
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WO97/43119 |
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Nov 1997 |
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WO |
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Primary Examiner: Ahmed; Sheeba
Attorney, Agent or Firm: Edwards Angell Palmer & Dodge
LLP
Claims
The invention claimed is:
1. A laminated sheet for molding comprising: a film layer which
comprises thermoplastic acrylic resin wherein the film layer is one
of transparent or translucent; an intermediate layer which
comprises a curable resin including at least one polyisocyanate
compound and an acrylic resin having hydroxyl groups, wherein the
curable resin is a cured material in a semi-cured state; and a
decorative layer having a mirror metallic luster, wherein the
decorative layer comprises a binder resin and fine metal grains
having a diameter of 5 to 25 .mu.m obtained from a thin metal film;
wherein the layers are laminated in the order stated.
2. The laminated sheet for molding according to claim 1, wherein
the curable resin includes the polyisocyanate compound and the
acrylic resin having hydroxyl groups; the acrylic resin having
hydroxyl groups has a glass transition temperature of 70 to
120.degree. C., a hydroxyl value of 10 to 100, and a weight average
molecular weight of 10,000 to 200,000; isocyanato groups included
in the polyisocyanate compound are in the range of 0.1 to 1.0
equivalent per 1 equivalent of hydroxyl groups in the acyrlic resin
having hydroxyl groups, and the cured material in a semi-cured
state contains remaining unreacted hydroxyl groups and unreacted
isocyanato groups.
3. The laminated sheet for molding according to claim 1, wherein
the decorative layer is a dried film of a gravure ink including a
binder resin and fine metal grains obtained from a thin metal
film.
4. The laminated sheet for molding according to claim 1, wherein a
substrate layer comprising a thermoplastic resin is further
provided on one surface of the decorative layer wherein the
intermediate layer is provided on the other surface.
5. The laminated sheet for molding according to claim 1, wherein
the semi-cured state is a state in which the reaction rate of
isocyanato groups of the polyisocyanate compound determined by an
infrared spectrophotometer is 50 to 80% with respect to a reaction
between isocyanato groups in the isocyanate compound and hydroxyl
groups in the acrylic resin having hydroxyl groups.
6. The laminated sheet for molding according to claim 1, wherein
the softening point of the acrylic resin of the film layer is in
the range of 60 to 300.degree. C.
7. The laminated sheet for molding according to claim 2, wherein
the hydroxyl value of the acrylic resin having hydroxyl groups is
40 to 100.
8. The laminated sheet for molding according to claim 1, wherein
the polyisocyanate compound has two or more isocyanato groups on
average in one molecule and has a number average molecular weight
of 10,000 or less.
9. The laminated sheet for molding according to claim 1, wherein
the thickness of the intermediate layer is 0.1 to 10 .mu.m.
10. The laminated sheet for molding according to claim 1, wherein
the decorative layer is a layer wherein the content of fine metal
grains based on nonvolatile content included in an ink is 10 to 60%
by mass.
11. The laminated sheet for molding according to claim 1, wherein
the fine metal grains are grains obtained from a vapor deposited
metal thin film of at least one selected from a group consisting of
aluminum, gold, silver, copper, titanium, chromium and nickel, or
grains selected from a group consisting of grains of brass, grains
of nickel chrome and grains of stainless steel.
12. The laminated sheet for molding according to claim 1, wherein
the thickness of the fine metal grains obtained from a thin metal
film is 0.01 to 0.1 .mu.m, and the diameter thereof is 10 to 15
.mu.m.
13. The laminated sheet for molding according to claim 1, wherein
the film thickness of the decorative layer is 0.05 to 3 .mu.m.
14. A production method of a laminated sheet for molding
comprising: a first step wherein a curable resin including at least
one polyisocyanate compound and an acrylic resin having hydroxyl
groups is applied to a thermoplastic acrylic resin film which is
one of transparent or translucent; a second step wherein a coating
film obtained by the application in the first step is semi-cured at
a temperature of 50.degree. C. or less to form an intermediate
layer in a semi-cured state; and a third step wherein a gravure ink
including a binder resin and fine metal grains obtained from a thin
metal film is printed on the intermediate layer in a semi-cured
state obtained in the second step to form a decorative layer with a
mirror metallic luster.
Description
TECHNICAL FIELD
The present invention relates to a laminated sheet for molding and
a production method thereof.
BACKGROUND ART
When a colored resin molded member is produced by a conventional
method, there is a method wherein spray coating or the like is
conducted after molding (a coating method), as well as a method in
which pigment is kneaded into a resin itself and the obtained
colored resin is injection-molded (a coloring method).
Particularly, when a design having a mirror-like (specular)
metallic luster is required, the coating method is used more
frequently than the coloring method, because kneading of a pigment
is difficult, a pigment flow trace is easily formed when the
coloring method is used, and so on. In the coating method, if a
coating film is heated to form a cross-linking, a surface
protection effect can also be expected. However, the use of
volatile organic solvent in a coating used for the coating method
is the mainstream procedure at present. Therefore, the use of
non-volatile organic solvent coating such as aqueous coating or
powder coating has been proposed from the standpoint of protection
of the operational environmental and external environmental from
volatile organic solvents discharged. However, it is difficult to
achieve a design having a mirror-like metallic luster using the
method at present. On the other hand, a method has been introduced
in which a colored sheet is laminated with a moldable resin support
layer and then they are co-cured by injection molding, instead of
conducting coating. The method makes it possible to produce a resin
molded member with a design having a mirror-like metallic luster
without the use of an organic solvent.
A sheet having a design of mirror-like metallic luster such as an
aluminum-deposited polyethylene terephthalate film and a laminated
sheet obtained by dry lamination of polypropylene film or the like
is known. Moreover, a laminated sheet having a layer consisting of
a cured film has been described in which the cured film is obtained
from a coating comprising an acrylic emulsion which contains
scale-like aluminum particles having a smooth surface. (For
example, please refer to Japanese Unexamined Patent Application,
First Publication No. H5-111991.)
However, although the surfaces of these sheets in a flat state have
designs having a mirror-like metallic lusters, the stretching
ability of a deposited surface of the sheets is insufficient.
Therefore, when mold processing such as a vacuum molding, in-mold
molding or the like is applied, retention of a design having a
mirror-like metallic luster becomes insufficient, and cracks,
luster irregularities and the like are caused.
Moreover, a laminated sheet having a cured film obtained from an
ink, in which fine metal grains are dispersed in a binder resin
varnish, is proposed. (For example, please refer to Japanese
Unexamined Patent Application, First Publication No. 2002-46230.)
Stretching ability can be improved by this method but it has the
drawback that luster of the sheet is inferior to luster of an
aluminum-deposited film or the like. In addition, the luster is
further reduced during vacuum molding, and luster irregularity is
caused.
An object of the present invention is to provide a laminated sheet
for molding, which has a good mirror-like metallic luster,
stretching ability necessary in molding, and less reduction of
luster even after molding is conducted, and maintains a design
having a good mirror-like metallic luster.
SUMMARY OF THE INVENTION
As a result of examinations in order to solve these problems, the
inventor achieved the present invention by providing an
intermediate layer made of a curable resin in a semi-cured state
between a transparent or translucent thermoplastic acrylic resin
film layer and a decorative layer having a mirror-like metallic
luster.
Specifically, the fist aspect of the present invention is a
laminated sheet for molding comprising: a film layer which
comprises thermoplastic acrylic resin wherein the film layer is one
of transparent or translucent; an intermediate layer which
comprises a curable resin including at least one polyisocyanate
compound and an acrylic resin having hydroxyl groups, wherein the
curable resin is a cured material in a semi-cured state; and a
decorative layer having a mirror-like metallic luster, which
comprises a binder resin and fine metal grains obtained from a thin
metal film; wherein the layers are laminated in the order
stated.
The second aspect of the present invention is a production method
of a laminated sheet for molding comprising:
a first step wherein a curable resin including a polyisocyanate
compound and an acrylic resin having hydroxyl groups is applied to
a thermoplastic acrylic resin film which is one of transparent or
translucent;
a second step wherein a coating film obtained by the application in
the first step is semi-curd at a temperature of 50.degree. C. or
less to form an intermediate layer in a semi-cured state; and
a third step wherein a gravure ink including a binder resin and
fine metal grains obtained from a thin film is printed on the
intermediate layer in a semi-cured state obtained in the second
step to form a decorative layer with a mirror-like metallic
luster.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic sectional view showing an example of a
laminated sheet for molding of the present invention.
FIG. 2 is a schematic sectional view showing an example wherein an
adhesive layer and a substrate layer are further provided on the
laminated sheet of FIG. 1.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A suitable example of present invention is described hereafter, but
the present invention is not limited to the following examples. For
example, constituents of these examples may also be properly
combined with each other.
The present invention relates to a laminated sheet for molding
having a design having a mirror-like metallic luster, and
particularly to a laminated sheet for molding, which is useful in
members for automobile parts, architectural materials, electrical
appliances and the like.
As shown in FIG. 1, the present invention can provide a laminated
sheet for molding 4 wherein a transparent or translucent
thermoplastic acrylic resin film layer 1, an intermediate layer 2
composed of a semi-cured material of a curable resin which includes
a polyisocyanate compound and an acrylic resin having hydroxyl
groups, and a decorative layer 3 having a mirror-like metallic
luster and including a binder resin and fine metal grains obtained
from a thin metal film are laminated in that order, and a
production method thereof. Embodiments thereof are described
below,
(Acrylic Resin Film Layer)
The transparent or translucent thermoplastic acrylic resin film
used in the laminated sheet for molding of the present invention is
a film which forms a surface layer of a molded article, and the
acrylic resin film is excellent in co-curing moldability and
weather resistance. It is preferable that the acrylic resin film be
a mono-layered or multilayered film wherein resin thereof has a
softening point in the range of 60 to 300.degree. C., preferably 70
to 220.degree. C. and more preferably 80 to 190.degree. C., since
molding processing using heat such as vacuum molding or the like is
conducted. The film may also include a colorant.
The film thickness of the film layer can be properly selected
according to demand. For example, it may be about 50 to 300 .mu.m,
and preferably 70 to 150 .mu.m.
(Intermediate Layer)
In the laminated sheet for molding of the present invention, a
transparent or translucent thermoplastic acrylic resin film is used
as a surface layer from the standpoint of ease of co-curing
molding, surface hardness and weather resistance. Therefore, when a
high-brightness ink for forming the decorative layer is directly
printed or applied on the thermoplastic acrylic resin film, the
film is easily eroded by organic solvent included in the
high-brightness ink. If the interface of the acrylic resin film and
the decorative layer loses its smoothness due to erosion, the
orientation of fine metal grains obtained from a thin metal film
included in the decorative layer becomes non-parallel to the
printing surface or coating surface, and the mirror-like metallic
luster easily deteriorates. The intermediate layer can be used for
protecting the surface of acrylic resin film from a solvent
included in the high-brightness ink used for forming the decorative
layer, and the intermediate layer can keep an interface position
with respect to the decorative layer smooth. The intermediate layer
can bury fine surface irregularities of the acrylic resin film,
increase adhesion strength as to the acrylic resin, and improve the
smoothness of the interface with the decorative layer. A solvent
included in a composition for forming the intermediate layer may
erode the surface of the acrylic resin that exists at the interface
of the acrylic resin film and the intermediate layer, but there is
no problem because the intermediate layer itself can form a smooth
surface for the decorative layer. The intermediate layer used in
the laminated sheet for molding of the present invention can be
composed of a curable resin a semi-cured state. The presence of the
intermediate layer can improve solvent resistance of the laminated
sheet against a solvent included in the high-brightness ink used
for forming the decorative layer. Furthermore, the intermediate
layer is a resin layer having crack resistance and is a
substantially transparent film. That is, the intermediate layer has
heat resistance, and due to heat resistance thereof, cracks are not
caused in the intermediate layer itself and in the laminated sheet
for molding during heat molding. In the present invention, a
"semi-cured state" means that the cured material in a semi-state
has a remaining unreacted hydroxyl group and unreacted isocyanato
group, and also means that the reaction rate of isocyanato groups
included in the polyisocyanate compound is 50 to 80%, preferably 60
to 80%, and more preferably 60 to 75%, with respect to the reaction
between isocyanato groups of the aforementioned polyisocyanate
compound and hydroxyl groups of the aforementioned acrylic resin
having hydroxyl groups. The reacion rate can be determined by using
an infrared spectrophotometer.
As the curable resin in a semi-cured state used in the intermediate
layer of the laminated sheet for molding of the preset invention, a
curable resin including an polyisocyanato compound and an acrylic
resin having hydroxyl groups can be selected from the standpoint of
ease of controlling a cross-linking reaction, weather resistance,
and adhesiveness to a transparent or translucent thermoplastic
acrylic resin film, and the like.
More specifically, it is preferable that the acrylic resin having
hydroxyl groups be an acrylic resin which has a hydroxyl value of
10 to 100, preferably 40 to 100, a weight average molecular weight
(a value based on polystyrene conversion) of 10,000 to 200,000, and
a glass transition temperature (Tg) of 70 to 120.degree. C., and
preferably 75 to 115.degree. C.
Due to the hydroxyl value of 10 or more, sufficient cross-linking
density of the cross-linked polymer can be achieved, and the
hardness and acid resistance of the polymer tend to be improved.
Due to the hydroxyl value of 100 or less, the three-dimensional
moldability tends to be improved. The particularly preferable range
of the hydroxyl value is 30 to 100.
Due to the weight average molecular weight of 10,000 or more, the
solvent resistance of the intermediate layer tends to be improved.
When the weight avenge molecular weight exceeds 200,000, leveling
property (smoothness) is lowered and the luster of the decorative
layer deteriorates. The weight average molar weight is more
preferably in the range of 20,000 to 100,000.
It is preferable that the glass transition temperature
(hereinafter, referred to as T.sub.g) of the acrylic resin having
hydroxyl groups, which can be obtained by the Fox formula, be 70 to
120.degree. C. The three dimensional moldability tends to be
improved when T.sub.g of the resin is 70.degree. C. or more.
Well-known conventional methods can be used to prepare the
aforementioned acrylic resin having hydroxyl groups. Examples of
especially typical methods include a method wherein an acrylic
monomer having a hydroxyl group(s), which is mainly used, is
copolymerized with other monomer, which can be selected as required
and is copolymerizable with the acrylic monomer.
Specific examples of acrylic monomers having a hydroxyl group(s),
which can be used as required to prepare an acrylic resin used in
the present invention in the aforementioned method, include:
hydroxyalkyl esters having two to eight carbons of acrylic acid or
methacrylic acid such as 2-hydroxyethyl acrylate, 2-hydroxypropyl
acrylate, 3-hydroxypropyl acrylate, hydroxybutyl acrylate,
2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate,
3-hydroxypropyl methacrylate, hydroxybutyl methacrylate and the
like; monoesters of a polyether polyol such as polyethylene glycol,
polypropylene glycol polybutylene glycol and the like, and an
unsaturated carboxylic acid such as acrylic acid, methacrylic acid
and the like; hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl
ether and the like; allyl alcohols; adducts of an
a,.beta.-unsaturated carboxylic acid and an monoepoxy compound such
as a-olefin epoxide and the like; monoethers of a polyether polyol
such as polyethylene glycol polypropylene glycol, polybutylene
glycol and the like, and a hydroxyl group-containing unsaturated
monomer such as 2-hydroxyethyl acrylate, 2-hydroxyethyl
methacrylate and the like; and adducts of glycidyl acrylate or
glycidyl methacrylate and a monobasic acid such as acetic acid,
propionic acid, p-tert-butyl benzoate, a fatty acid and the like;
adducts of the aforementioned hydroxyl group-containing monomers
and lactones (for example, e-caprolactone, .gamma.-valerolactone
and the like).
Examples of the aforementioned other monomer which can be
copolymerized with the acrylic monomer include: alkyl esters or
cycloalkyl esters having one to twenty two carbons of acrylic acid
or methacrylic acid, such as n-propyl methacrylate, isopropyl
methacrylate, (n-, iso- or tert-) butyl methacrylate, hexyl
methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl
methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl
methacrylate and the like; alkoxy-alkyl esters having two to
eighteen carbons of acrylic acid or methacrylate acid, such as
methoxybutyl acrylate, methoxybutyl methacrylate, methoxyethyl
acylate, methoxyethyl methacrylate, ethoxybutyl acrylate,
ethoxybutyl methacrylate and the like; aminoalkyl acrylates such as
N,N-dimethylaminoethyl(meth)acrylate,
N,N-diethylaminoethyl(meth)acrylate,
N-tert-butylaminoethyl(meth)acrylate.
N,N-diethylaminopropyl(meth)acrylate and the like; acrylamide
monomers such as acrylamide, methacrylamide,
N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide,
N-butyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide and the like;
unsaturated monocarboxylic acids such as acrylic acid, methacrylic
acid and the like; carboxyl group-containing monomers such as
unsaturated dicarboxylic acids such as maleic acid, itaconic acid,
fumaric acid, and mesaconic acid, and anhydrides, half esters and
modified compounds thereof and the like; monoester compounds or
diester compounds obtained from glycols such as ethylene glycol,
1,6-hexanediol, neopentyl glycol, and the like, and an acid
anhydride group-containing unsaturated compound such as maleic
anhydride, itaconic anhydride and the like; glycidyl
group-containing monomers such as glycidyl acrylate, glycidyl
methacrylate and the like; vinyl aromatic compounds such as
styrene, a-methyl styrene, vinyl toluene and the like; and
ethylene, propylene, 1-butylene, 2-butylene, acrylonitrile, vinyl
acetate, vinyl chloride and the like.
The acrylic resin having hydroxyl groups can be prepared by using
various monomers as described above and by using various
conventional polymerization processes such as a solution
polymerization method, non-aqueous dispersion polymerization
method, block polymerization method or the like. Among these
processes, a radical polymerization method conducted in an organic
solvent, which is known as a solution radical polymerization
method, is particularly recommended because it is the most simple
method.
In the production method, the aforementioned monomer components can
be reacted at a reaction temperature of about 60 to 160.degree. C.
for about 1 to 30 hours in an organic solvent with a radical
polymerization initiator such as an organic peroxide compound such
as benzoyl peroxide; azo compounds such as
N,N-azabisdiisobutyronitrile; a chain transfer agent such as
n-dodecyl mercaptan; and/or the like. Examples of the organic
solvent include: aromatic hydrocarbons such as xylene and toluene;
alcohols such as isopropyl alcohol, isobutanol, and n-butanol;
esters such as ethyl acetate, and butyl acetate; ketones such as
methyl amyl ketone; and ethers such as cellosolve, butyl
cellosolve, and cellosolve acetate.
It is preferable that the polyisocyanate compound, which is used
for the laminated sheet for molding of the present invention, that
is, the polyisocyanate compound(s) usable for forming the
intermediate layer which is a curable resin in a semi-cured state,
has two or more isocyanate groups on the average in one molecule
and a number average molecular weight (a value based on polystyrene
conversion) of 10,000 or less, more preferably 150 to 5,000, and
particularly preferably 2,000 or less. In the present invention,
"has two or more isocyanate groups on the average in one molecule"
means that an isocyanate compound(s) having three or more
isocyanate groups in one molecule (herein after, referred to as a
trivalent or multivalent isocyanato compound) can be included as a
necessary isocyanate compound component in the polyisocyanato
compound used.
Specific examples of trivalent or multivalent to compounds include:
aliphatic triisocyanates such as 2-isocyanatoethyl-2,6-diisocyanato
caproate, 1,3,5-cyclohexane triisocyanate, 2,4,6-cycloheptane
triisocyanate, 1,2,5-cyclooctane triisocyanate and the like; and
aromatic triisocyanates such as 1,3,5-benzene triisocyanate,
2,4,6-naphthalene triisocyanate and the like; polyisocyanates
having a so-called isocyanurate ring structure obtained by cyclic
trimerization of diisocyanate. It is preferable that an isocyanate
compound(s) selected from bivalent isocyanate compounds, that is
diisocyanates, be used in combination with the trivalent or
multivalent organic polyisocyanate compound(s).
Examples of the diisocyanates include: aliphatic diisocyanates such
as hexamethylene diisocyanate, trimethyl hexamethylene
diisocyanate, dimeric acid diisocyanate, lysine diisocyanate and
the like; cyclic aliphatic diisocyanates such as hydrogenated
xylene diisocyanate, cyclohexylene diisocyanate, 1,3-bisisocyanato
methylcyclohexane, 2-methyl-1,3-diisocyanato cyclohexane,
2-methyl-1,5-diisocyanato cyclohexane, methylene
bis(cyclohexylisocyanate), isophorone diisocyanate and the like;
and aromatic diisocyanates such as tolylene diisocyanate, phenylene
diisocyanate, diphenylmethane diisocyanate, m-xylene diisocyanate,
4,4'-diphenylmethane diisocyanate xylylene diisocyanate, a,a,a',
a'-tetramethyl-m-xylene diisocyanate, tetramethylxylylene
diisocyanate, naphthalene diisocyanate and the like.
Moreover, the trivalent or multivalent isocyanato compound can also
be used in combination with the following compounds. For example,
the trivalent or multivalent isocyanato compound can be used
together with: a dimer or trimer of an isocyanato compound which
has two or more valences; adducts and the like which are made by
reacting the isocyanato compound, which has two or more or three or
more valences, and polyhydric alcohols, low molecular weight
polyester resins, water and/or the like in a condition of excess
isocyanato groups; blocked polyisocyanates wherein free isocyanato
groups of an isocyanate compound having free isocyanato groups are
blocked with a blocking agent such as phenols, oximes, lactams,
alcohols, mercaptans and the like; polyisocyanates having a biuret
structure obtained by reacting water and polyisocyanates having a
free isocyanato group; homopolymers of vinyl monomers having an
isocyanato group such as 2-isocyanato ethyl(meth)acrylate,
3-isopropenyl-a,a-dimethylbenzyl isocyanate or (meth)acryloyl
isocyanate; or various vinyl copolymers such as isocyanato
group-containing acrylic copolymers, vinyl ester copolymers,
fluoroolefins copolymers and the like, which are obtained by
copolymerizing the isocyanato group-containing vinyl monomer with
acrylic monomer, vinyl ester monomer, vinyl ether monomer, aromatic
vinyl or fluoroolefin vinyl monomer, or the like.
As the blend ratio of the acrylic resin having hydroxyl groups to
the polyisocyanate compound used for the intermediate layer, which
is a curable resin in a semi-cured state included in the laminated
sheet for molding of the present invention, it is preferable that
isocyanato groups included in the polyisocyanate compound be in the
range of 0.1 to 1.0 equivalent per 1 equivalent of hydroxyl groups
included in the acrylic resin having hydroxyl groups from the stand
point of the balance of various properties, and more preferably in
the range of 0.1 to 0.6 equivalent. It is preferable that the
thickness of the intermediate layer be 0.1 to 10 .mu.m, and more
preferably 0.5 to 5 .mu.m.
When a curable resin including the aforementioned acrylic resin
having hydroxyl groups and a polyisocyanate compound is reacted to
be cured, a curing catalyst can be included if necessary. Examples
of representative curing catalysts include: various amine compounds
such as N-methylmorpholine, pyridine,
1,8-diazabicyclo[5,4,0]undecene-7 (DBU),
1,5-diazabicyclo[4,3,0]nonene-5 (DBN),
1,4-diazabicyclo[2,2,2]octane (DABCO), tri-n-butylamine or
dimethylbenzylamine, butylamine, octylamine, monoethanolamine,
diethanolamine, triethanolamine, imidazole, 1-methylimidazole,
2,4-dimethylimidazole, 1,4-diethylimidazole, 3-aminopropyl
trimethoxysilane, 3-aminopropyl triethoxysilane,
3-(N-phenyl)aminopropyl trimethoxysilane,
3-(2-aminoethyl)aminopropyl trimethoxysilane,
3-(2-aminoethyl)aminopropylmethyl dimethoxysilane and the like;
so-called quaternary ammonium salts such as tetramethyl ammonium
salts, tetrabutyl ammonium salts, trimethyl(2-hydroxypropyl)
ammonium salts, cyclohexyltrimethyl ammonium salts,
tetrakis(hydroxylmethyl) ammonium salts, dilauryldimethyl ammonium
salts, trioctylmethyl ammonium salts,
o-trifluoromethylphenyltrimethyl ammonium salts, wherein examples
of typical counter ions thereof can include chloride, bromide,
carboxylate, hydroxide and the like; and various organometallic
compounds such as dibutyltin dilaurate, dibutyltin acetate, lead
dioctylate, cobalt naphthenate and the like. Moreover, the
intermediate layer may include a colorant for imparting a
design.
Pigment can be preferably employed as a colorant used in the
intermediate layer. The employable pigments are not especially
limited, and well-known pigments such as coloring pigments,
metallic pigments, interference color pigments, fluorescent
pigments, extender pigment and the like can be used. Examples of
coloring pigments include: organic pigments such as quinacridone
type pigments such as quinacridone red and the like; azo type
pigments such as pigment red and the like; phthalocyanine type
pigments such as phthalocyanine green and the like; perylene type
pigments such as perylene red and the like; and inorganic pigments
such as titanium oxide, carbon black and the like. Examples of
metallic pigments include aluminum powder, nickel powder, copper
powder, brass powder, chrome powder and the like.
Examples of interference color pigments include pearl mica powder
having a nacreous luster, colored nacreous pearl mica powder having
a nacreous luster and the like. Examples of fluorescent pigments
include synthetic resin solid solution type pigments, in which
fluorescent dye such as basic yellow, rhodamine B and the like is
included in melamine resin or the like in a solid-solute state.
Examples of extender pigment include inorganic pigments such as
barium sulfate, calcium carbonate and the like. The pigment can be
directly added as it is, or can be added in a conventional state of
colorants used for plastic, such as in a form of color compounds,
concentrated master batch, powder colorants, granular colorants,
liquid colorants or the like.
These pigments may be used alone, or in combination of two or
more.
If required, in order to prevent the occurrence of cracks at the
time of stretching, the intermediate layer used in the laminated
sheet for molding of the present invention may comprise one or more
kinds of thermoplastic resins, such as polypropylene, polyethylene,
ethylene-vinyl acetate copolymer (hereinafter, referred to as EVA),
polyisobutylene, polybutadiene, polystyrene, polycarbonate,
polymethylpentene, ionomers, acrylonitrile-butadiene-styrene
copolymer (hereinafter, referred to as ABS), polyvinyl chloride,
polyvinylidene chloride, acrylic resins, polyvinyl alcohol,
polyamide resins, polyacetals, polyesters, modified polyphenylene
ethers, alkyd resins, silicon resins, fluoro resins and the like,
in so far as properties of the finally obtained product are not
affected by the resins.
The laminated sheet for molding of the present invention can
maintain a good mirror-like metallic luster even after molding,
since the intermediate layer is adjacent to the decorative layer
having a mirror-like metallic luster including a binder resin and
fine metal grains. However, if necessary, a printing ink layer
including a colorant may be formed between the intermediate layer
and the decorative layer partly. Furthermore, as well as a section
between the intermediate layer and the decorative layer, the
printing ink layer including a colorant may be formed on the whole
of or a part of another section in the laminated sheet, for
example, the top surface of the acrylic resin film layer, between
the acrylic resin film layer and the intermediate layer, between
the decorative layer and the substrate layer, or the like
The intermediate layer which comprises a curable resin in a
semi-cured state can be formed by a process comprising: printing or
applying a curable resin on a transparent or translucent
thermoplastic acrylic resin film, and semi-curing the obtained
coating film at a temperature of 50.degree. C. or below. For
example, in the semi-curing step, the coating film is preferably
maintained at 40 to 50.degree. C. for 3 to 4 days. Examples of
usable printing or coating methods include: printing methods such
as gravure printing, flexo graphic printing, screen printing and
the like; and coating methods such as a gravure coater method, a
gravure reverse coater method, a flexo graphic coater method, a
blanket coater method, a roller coater method, a knife coater
method, an air knife coater method, a kiss touch coater method, a
kiss touch reverse coater method and a comma coater method, a comma
reverse coater method, a micro-gravure coater method and the
like.
(Decorative Layer)
The decorative layer of the laminated sheet for molding of the
present invention can be formed by printing or applying a
high-brightness ink, in which fine metal grains obtained from a
thin metal film is dispersed in a binder resin varnish, on the
intermediate layer comprising the aforementioned curable resin in a
semi-cured state. Gravure inks, screen inks and the like can be
used as the high-brightness ink. It is preferable that gravure ink
is used in order to arrange (orient) the fine metal grains obtained
from a thin metal film uniformly and to arrange the grains in
parallel each other. The content of the fine metal grains, which is
obtained from a thin metal film, based on nonvolatile matter
included in the ink is in the range of 10 to 60% by mass, and
preferably 20 to 45% by mass. A metallic powder is commonly used in
a metallic ink. However, when fine metal grains obtained from a
thin metal film is used in a metallic ink and the metallic ink is
printed or applied to form an object, an excellent coated or
printed object can be obtained since the surfaces of the fine metal
grains can face in parallel to the surface of the object, and
consequently a high-brightness mirror-like metallic luster can be
provided. Such high-brightness can not be achieved by the metallic
powder commonly used.
Examples of metal usable for the fine metal grains included in the
high-brightness ink used for in the decorative layer include,
aluminum, gold, silver, copper, brass, titanium, chromium, nickel,
nickel chrome, stainless steel and the like. Said metals may be
used alone, or in combination of two or more in a mixed state.
Examples of a method for making metal object or the like into a
thin metal film include: a vapor deposition method usable for
metals having a low-melting point such as aluminum; a stretch
method usable for metals having stretching ability such as gold,
silver, copper and the like; and a sputtering method usable for
metals which have a high melting point and do not have stretching
ability. Among them, fine metal grains, which are obtained from a
vapor-deposited metal thin film, are preferably used. The thickness
of the fine metal grains, which are obtained from a metal thin
film, is preferably 0.01 to 0.1 .mu.m, more preferably 0.02 to 0.08
.mu.m, and even more preferably 0.02 to 0.045 .mu.m. The diameter
of the fine metal grains which is dispersed in the ink, is
preferably 5 to 25 .mu.m, and more preferably 10 to 15 .mu.m. If
the grain diameter is less than 5 .mu.m, the brightness of the
coating film becomes insufficient, and if the grain diameter is
greater than 25 .mu.m, it is difficult for the fine metal grains to
orient in parallel, and therefore the brightness thereof is
reduced, and clogging tends to be caused in a plate when ink is
printed or applied by the gravure method or screen printing method.
The diameter of the fine metal grains can be measured by the
coulter counter method, microscopic observation method, laser
diffraction method or the like, and the average size of the flat
surface part of the fine metal grains is provided as the grain
diameter.
Hereinafter, an example of a method of preparing a thin metal film
and fine metal grains obtained from the film is described by using
an especially preferable vapor deposition method. A polyolefin
film, a polyester film or the like can be used as support film for
depositing a metal. After a peeling layer is provided on the
support film by coating, a metal is deposited on the peeling layer
to have a predetermined thickness. Then, a top coat layer can be
provided on the deposition film surface by application in order to
prevent oxidation of the deposition film. The same coating agent
can be used for the formation of the peeling layer and the top coat
layer.
Resins used in the peeling layer and the top coat layer are not
especially limited. Specific examples of the resins include
cellulose derivatives, acrylic resins, vinyl resins, polyamides,
polyesters, EVA resins, chlorinated polypropylenes, chlorinated EVA
resins, petroleum resins and the like. Examples of solvents usable
for the resin include: aromatic hydrocarbons such as toluene,
xylene and the like; aliphatic or alicyclic hydrocarbons such as
n-hexane, cyclohexane and the like; esters such as ethyl acetate,
propyl acetate and the like; alcohols such as methanol, ethanol,
isopropyl alcohol and the like; ketones such as acetone, methyl
ethyl ketone and the like; and alkylene glycol monoalkyl ether such
as ethylene glycol monoethyl ether, propylene glycol monomethyl
ether and the like.
The above metal deposition film is immersed in a solvent, which can
dissolve the peeling layer and the top coat layer, and then
stirring is conducted to peel the metal deposition film from the
support film. Then, it is further stirred to make fine metal grains
having a diameter of about 5 to 25 .mu.m, preferably 10 to 15
.mu.m, from the thin metal deposition film, and then filtration and
drying are conducted. The solvent is not especially limited except
that it must be a solvent which can dissolve the resins used in the
peeling layer and the top coat layer. When the metal thin film is
prepared by a sputtering method, fine metal obtained from the thin
film can be obtained similar to the method described above. When a
metal foil is used, the metal foil itself can be pulverized in a
solvent by using a stirring apparatus to form grains having a
predetermined size.
The fine metal grains obtained from a thin metal film are
preferably surface-treated to increase dispersibility thereof in
ink. Examples of surface-treating agents include: organic fatty
acids such as stearic acid, oleic acid, palmitic acid and the like;
and cellulose derivatives such as nitrocellulose, cellulose acetate
propionate, cellulose acetate butyrate and ethyl cellulose, and
methylsilyl isocyanate.
As a binder resin employed in the decorative layer, resins used for
conventional gravure ink, flexo graphic ink, screen ink or resins
commonly employed in coatings can be used. Specific examples of
binder resin preferably used for coatings include: acrylic resin,
vinyl chloride resin, vinylidene chloride resin, vinyl
chloride-vinyl acetate resin, ethylene-vinyl acetate resin,
polyolefin resin, chlorinated olefin resin, ethylene-acrylic resin,
polyurethane resin, polyamide resin, urea resin, epoxy resin,
polyester rein, petroleum resin, cellulose derivative resin and the
like. Moreover, resins, in which a polar group such as carboxyl
group, phosphoric acid group, sulfonic acid group, amino group,
quaternary ammonium salt group or the like is chemically combined
therein, may be used alone or in combination with other resins.
If necessary, various additives which can be employed in
conventional gravure ink, flexo graphic ink, screen ink, coatings
or the like can be included in the high-brightness ink used for the
decorative layer, in order to provide antiforming properties,
sedimentation preventing properties, pigment dispersing properties,
fluidity modification, blocking inhibiting properties, antistatic
properties, oxidation inhibiting property, photo stability, UV
absorption, internal cross-linking and/or the like, in so far as
the design and stretching ability are not inhibited by the
additives. Examples of additives include coloring pigments, dyes,
waxes, plasticizers, leveling agents, surfactants, antifoaming
agents, chelating agents, polyisocyanates and the like.
The film thickness of the decorative layer can be determine as
required. The thickness is preferably 0.05 to 3 .mu.m, more
preferably 0.5 to 2 .mu.m, and even more preferably 1 to 2
.mu.m.
The high-brightness ink usable in the decorative layer is a solvent
type ink. Well-known conventional solvents which can be employed in
conventional gravure ink, flexo graphic ink, screen ink, coatings
and the like can be used for the ink. Specific examples of solvents
include: aromatic hydrocarbons such as toluene, xylene and the
like; aliphatic or alicylic hydrocarbons such as n-hexane,
cyclohexane and the like; esters such as ethyl acetate, propyl
acetate and the like; alcohols such as methanol, ethanol, isopropyl
alcohol and the like; ketones such as acetone, methyl ethyl ketone;
and alkylene glycol monoalkyl ethers such as ethylene glycol
monoethyl ether, propylene glycol monomethyl ether and the
like.
The grain diameter of the fine metal grains, which are blended into
a high-brightness ink used for the decorative layer of the
laminated sheet for molding of the present invention, is preferably
5 to 25 .mu.m, and more preferably 10 to 15 .mu.m. When kneading
using a roller mill or the like is conducted, the fine metal grains
obtained from a thin film become very fine particles, and the
metallic luster deteriorates extremely. Accordingly, kneading is
not conducted in the present invention, and raw materials
comprising the aforementioned binder resin, the fine metal grains
obtained from a thin film and the solvent can be simply mixed with
a mixer to form an ink.
(Substrate Layer)
The laminated sheet for molding of the present invention may
include a substrate layer which comprises a thermoplastic resin,
such that the substrate layer is provided on one surface of the
decorative layer, wherein an intermediate layer is provided on the
other surface thereof.
A sheet which includes thermoplastic resin as a main component can
be used for the substrate layer, since a molding process using heat
such as vacuum molding or the like is conducted. Moreover, when a
laminated sheet for molding obtained after vacuum molding is
further subjected to injection molding, it is preferable that a
thermoplastic resin substrate sheet be selected so that the sheet
can have good adhesiveness with a resin used in injection
molding.
For these reasons, examples of resins usable for the substrate
layer include: general purpose resins such as
acrylonitrile/butadiene/styrene resins (ABS), acrylonitrile/acrylic
rubber/styrene resins (AAS), acrylonitrile/ethylene rubber/styrene
resins (AES), polyethylene resins (PE), polypropylene resins (PP),
vinyl chloride resins (PVC) and the like, and thermoplastic
elastomers (TPE) such as olefin elastomers (TPO), vinyl chloride
elastomers (TPVC), styrene elastomers (SBC), urethane elastomers
(TPU), polyester elastomers (TPEE), polyamide elastomers (TPAE) and
the like. These materials may be used alone or by mixing (blending)
two or more. The substrate layer may be a laminated sheet obtained
by extruding materials each having different characteristics
together. The substrate layer may be constructed from plural
layers.
(Adhesive Layer)
Examples of a method for further laminating a substrate layer
selected from aforementioned various resin sheets on a printed or
applied decorative layer include: a method wherein an adhesive is
interposed as an adhesive layer 5 between an decorative layer 3 and
a substrate layer 6 as shown in FIG. 2; and a method wherein an
adhesive is not interposed. Examples of preferable adhesives
include dry laminate adhesive, wet laminate adhesive, heat seal
adhesive, hot melt adhesive and the like. A thermal laminate which
does not use a specific adhesive layer can also be used. In such
case, a resin which shows adhesiveness in a range from ordinary
temperatures to about 60.degree. C. may be used as a binder resin
for the decorative layer.
A layer having stickiness can be provided in place of the adhesive
layer. Examples of agents for providing stickiness include: acrylic
type agent, rubber type agent polyalkyl silicon type agent,
urethane type agent, and polyester type agent and the like.
(Printing or Applying Method)
Examples of printing and applying methods for the decorative layer
and for providing an adhesive usable for the laminated sheet for
molding of the present invention include: printing methods such as
gravure printing, flexo graphic printing, screen printing and the
like; and applying methods such as a gravure coater method, a
gravure reverse coater method, a flexo graphic coater method, a
blanket coater method, a roller coater method, a knife coater
method, an air knife coater method, a kiss touch coater method, a
kiss touch reverse coater method and a comma coater method, a comma
reverse coater method, a microgravure coater method and the
like.
(Other)
In the laminated sheet for molding of the present invention, one or
more top coat layers, which are transparent, translucent, and/or
colored clear layer, can be provided on the laminated sheet at a
surface side of a molded product (on a surface side of the acrylic
resin film layer), in order to impart properties such as excellent
design, friction resistance, scratch resistance, weather
resistance, contamination resistance, water resistance, chemical
resistance and heat resistance and the like. Examples of top coat
agents to be used for forming the top coat layer include: lacquer
type agent, cross-linking type agent which include isocyanate or
epoxy and the like, UV cross-linking type agent, and EB
cross-linking type agent.
The laminated sheet for molding of the present invention can be
used for various molding processes as a surface layer of a molded
product which can be manufactured by the molding processes. For
example, an insert injection molding method can be used, wherein
the laminated sheet for molding of the present invention is placed
such that the transparent or translucent thermoplastic acrylic
resin film thereof is positioned on the upper side, and then the
laminated sheet is made into a preliminary molded article having a
three-dimensional shape by a method of heat molding, and then the
preliminary molded article obtained is inserted into an injection
molding metal die to be integrated with an injected resin.
Moreover, it can also be used for an in-mold injection molding
process wherein a laminated sheet for molding of the present
invention, which maintains a sheet shape, is inserted into an
injection molding metal die and then integrated with an injected
resin in a metal die. Due to excellent stretching ability of the
laminated sheet for molding of the present invention, excellent
design, that is mirror-like metallic luster, can be kept even in a
portion where it is stretched to a high degree.
In the present invention, the stretching ability is evaluated as
followed from a standpoint of crack resistance. The crack
resistance can be determined based on cracks occurring in the sheet
after molding. At first the mold processing is conducted at a
temperature higher than the softening point of materials included
in a laminated sheet for molding (for example, sheet temperature:
about 100 to 170.degree.). Subsequently, the thickness of the
laminated sheet for molding is measured, and whether or not cracks
exist is visually determined at a section having 1/2 thickness
based on the thickness before the mold processing (a section where
the surface area is stretched to have twice its original area,
called a 200% stretched part). A case where cracks occur is
represented as "x", a case where no cracks occur is represented as
".largecircle.", and a case where cracks cannot be visually found
but fine cracks are found if it is observed under a microscope with
a magnification of 200 to 500 times is represented as ".DELTA.".
Regarding the laminated sheet for molding of the present invention,
a state of ".largecircle." to ".DELTA." where no cracks occur at
the macroscopic level in a 200% stretched part is considered
acceptable. Similarly, the luster is measured and cracks are
visually checked for after stretching, in a section of a 130%
stretched part where the thickness becomes 1/1.3 times, that is,
the surface area becomes 1.3 times the original area, and in a
section of a 150% stretched part where the thickness becomes 1/1.5
times, that is, the surface area becomes 1.5 times the original
area.
In the present invention, the variation of brightness of a
stretched sheet is evaluated as a change rate of surface luster
value determined by using a gloss meter:
MIRROR-TRI-GLOSS (manufactured by BYK-Gardner Corporation) under
conditions of 20.degree. C./20.degree. C., wherein measurement is
conducted from the side of a transparent or translucent
thermoplastic acrylic resin film of the sheet. Change rate of
surface luster value=(luster value of non-stretched part-luster
value of stretched part)/(luster value of non-stretched
part).times.100(%)
In the present invention, it is preferable that the change rate of
surface luster be 30% or less, and more preferably 25% or less,
with respect to the 130% stretched part, 150% stretched part and
200% stetcher part of the laminated sheet.
The mold processing is conducted by vacuum molding under conditions
of sheet temperate of 155.degree. C. and metal die temperature of
60 to 80.degree. C. using a test metal die having a trapezoidal
shape, which has a square top surface having 5 cm sides, a bottom
square surface having 7 cm sides, and side surfaces having 2 cm
sides, such that sheet holding position is changed so that the area
of a sheet provided on the top surface is stretched to 130%, 150%
or 200% size.
EXAMPLES
The present invention is specifically described by using examples
below, but it is not restricted to these examples. The terms
"parts" and "%" in the examples represent "parts by mass" and "% by
mass".
(1) Fine Grains Obtained from an Aluminum Thin Film
A nitrocellulose (HIG7) was dissolved in a mixed solvent (ethyl
acetate:isopropyl alcohol=6:4) to prepare a 6% solution. The
solution was applied on a polyester film by using a gravure
cylinder having a screen line number of 175 (lines/inch) and a cell
depth of 25 .mu.m to form a peeling layer. After the layer was
completely dried, aluminum was deposited on the peeling layer so
that the thickness of aluminum became 0.04 .mu.m. Then, a
nitrocellulose solution which was the same as those used in the
peeling layer was applied under the same conditions to form a top
coat layer on the deposited surface.
The aforementioned deposited film was immersed in a mixed solvent
(ethyl acetate:isopropyl alcohol=6:4) to peel off the aluminum
deposited film from the polyester film, and then the aluminum
deposited film was pulverized by using a stirring apparatus so that
the size of grains obtained from the aluminum deposited film became
about 150 .mu.m, and aluminum grains obtained from the thin
aluminum film was prepared.
(2) Slurry of Aluminum Fine Grains Obtained from an Aluminum Thin
Film
TABLE-US-00001 Aluminum grains obtained from an aluminum thin film
10 parts Ethyl acetate 35 parts Methyl ethyl ketone 30 parts
Isopropyl alcohol 30 parts
5 parts of a nitrocellulose solution having the following
composition was added while mixing and stirring the above
components.
TABLE-US-00002 Nitrocellulose (HIG1/4) 25 parts Mixed solvent
(ethyl acetate:isopropyl alcohol = 6:4) 75 parts
The mixture obtained was stirred until the size of the fine
aluminum grains became 5 to 25 .mu.m by using a turbo mixer while
keeping the temperature at 35.degree. C. or below to prepare a
slurry of fine aluminum grains (non-volatile matter: 10%).
(3) Intermediate Layer
Synthesis example of acrylic resin having hydroxyl groups used in
the intermediate layer is given below.
In the example, the weight average molecular weight described is a
polystyrene conversion value which was obtained as a result of GPC
measurement. Each solid content was calculated based on mass after
drying. The mass after drying was obtained such that 1 g of a
sample provided in an aluminum dish was spread thinly and uniformly
with toluene, and it was air-dried, and then the sample was further
dried in a hot air dryer at 108.degree. C. for 1 hour. The hydroxyl
value thereof was calculated as a KOH neutralization amount based
on the composition of used monomers. The polymer T.sub.g was
measured by DSC, and the acid value was determined using a
titration method using a solution of 0.05 moldm.sup.-3 potassium
hydroxide-toluene.
(Synthesis Example 1 of Acrylic Resin Having Hydroxyl Groups)
Into a reaction vessel equipped with a temperature regulator, a
nitrogen inlet tube, dropping devices (two) and a stirring device,
850 parts of butyl acetate and 1 part of PERBUTYL Z (trade name,
manufactured by NOF corporation, t-butyl peroxybenzoate, "PERBUTYL"
is a registered trade name of this company) were poured, and after
replacement of air in the vessel with nitrogen, the mixture was
heated to 110.degree. C. over 1.5 hours.
Separately, a solution prepared by well mixing 660 parts of methyl
methacrylate, 150 parts of t-butyl methacrylate and 190 parts of
2-hydroxyethyl methacrylate (hereinafter, referred to as a monomer
solution) and a solution prepared by well mixing 200 parts of
isobutyl acetate, 9 parts of PERBUTYL O (trade name, manufactured
by NOF corporation, t-butyl peroxy-2-ethyl hexanoate) and 2 parts
of PERBUTYL Z (trade name, manufactured by NOF corporation, t-butyl
peroxybenzoate) (hereinafter, cited as a catalyst solution) were
poured into each of the dropping devices, and then nitrogen
replacement was conducted immediately.
The aforementioned monomer solution and catalyst solution were
dropped into the reaction vessel over 5 hours in a nitrogen
atmosphere while the reaction temperature was monitored to ensure
that it did not rise rapidly. After the completion of dropping,
stirring was conducted for about 15 hours to obtains resin
composition (O-1) having 60% solid content. The weight average
molecular weight of the obtained resin was 100,000, the hydroxyl
value of the solid was 79, and T.sub.g was 95.degree. C.
(Synthesis Example 2 of an Acrylic Resin Having Hydroxyl
Groups)
Into a reaction vessel equipped with a temperature regulator, a
nitrogen inlet tube, dropping devices (two) and a stirring device,
850 parts of butyl acetate and 1 parts of PERBUTYL Z (trade name,
manufactured by NOF corporation, t-butyl peroxybenzoate) were
poured, and after replacement of air in the vessel with nitrogen,
heated to 110.degree. C. over 1.5 hours while stirring.
Separately, a solution prepared by well mixing 650 parts of methyl
methacrylate, 100 parts of n-butyl methacrylate, 40 parts of
2-ethylhexyl methacrylate, 165 parts of 2-hydroxyethyl acrylate, 40
parts of allyl methacrylate and 5 parts of methacrylic acid
(hereinafter, referred to as a monomer solution) and a solution
prepared by well mixing 200 parts of isobutyl acetate, 11 parts of
PERBUTHY O (trade name, manufactured by NOF corporation, t-butyl
peroxy-2-ethylhexanoate) and 2 parts of PERBUTHY Z (trade name,
manufactured by NOF corporation, t-butyl peroxybenzoate)
(hereinafter, cited as a catalyst solution) were poured each of the
dropping devices, and then nitrogen replacement was conducted
immediately.
The aforementioned monomer solution and catalyst solution were
dropped into the reaction vessel over 5 hours in a nitrogen
atmosphere while the reaction temperature was monitored to ensure
that it did not rise rapidly. After the completion of dropping,
stirring was conducted for about 15 hours, and as a result, a resin
composition (O-2) having 51% solid content was obtained. The
weight-average molecular weight of the obtained resin was 16,800,
the hydroxyl value of the solid thereof was 72, and T.sub.g was
72.degree. C.
(Synthesis Example 3 of an Acrylic Resin Having Hydroxyl
Groups)
Into a reaction vessel equipped with a temperature regulator, a
nitrogen inlet tube, dropping devices (two) and a stirring device,
800 parts of isobutyl acetate and 1 parts of PERBUTYL Z (trade
name, manufactured by NOF corporation, t-butyl peroxybenzoate) were
poured, and after replacement of air in the vessel with nitrogen,
the mixture was heated to 110.degree. C. over 1 hour while
stirring.
Separately, a solution prepared by well mixing 600 parts of methyl
methacrylate, 100 parts of n-butyl methacrylate, 295 parts of
PLACCEL FM-1 (trade name, manufactured by Daicel Chemical
Industries, Ltd., lactone modified methacrylate, "PLACCEL" is a
registered trade name of this company) and 5 parts of methacrylic
acid (hereinafter, referred to as a monomer solution) and a
solution prepared by well mixing 185 parts of butyl acetate, 10
parts of PERBUTYL O (trade name, manufactured by NOF corporation,
t-butyl peroxy-2-ethylhexanoate) and 2 parts of PERBUTYL Z (trade
name, manufactured by NOF corporation, t-butyl peroxybenzoate)
(hereinafter, referred to as a catalyst solution) were charged into
each of the dropping devices, and then nitrogen replacement was
conducted immediately.
The aforementioned monomer solution and catalyst solution were
dropped into the reaction vessel over 4 hours in a nitrogen
atmosphere while the reaction temperature was monitored to ensure
that it did not rise rapidly. After the completion of dropping,
stirring was conducted for about 16 hours, and a resin composition
(O-3) having 52% solid content was obtained. The weight-average
molecular weight of the obtained resin was 115,000, the hydroxyl
value of the solid was 68, and T.sub.g was 55.degree. C.
(Polyisocyanate Compounds)
"BURNOCK DN-980" (trade name, manufactured by Dainippon Ink and
Chemicals, Incorporated, a polyisocyanate containing an
isocyanurate ring, number average molecular weight: 800,
nonvolatile content: 75% (solvent: ethyl acetate), number of
functional groups 3, NCO concentration 15%, "BURNOCK" is a
registered trade name of this company) was used as a polyisocyanate
compound (N-1).
"BURNOCK DN-981" (trade name, manufactured by Dainippon Ink and
Chemicals, Incorporated, a polyisocyanate containing an
isocyanurate ring, number average molecular weight: about 1,000,
non-volatile content: 75% (solvent: ethyl acetate), number of
functional groups 3, NCO concentration 13 to 14%) was used as a
polyisocyanate compound (N-2).
A solution for forming an intermediate layer was prepared by
blending the above acrylic resin having hydroxyl groups (O-1 to 3)
and polyisocyanate compounds (N-1 to 2) at a predetermined ratio
and then mixing.
(4) Ink
(Preparation Example of Ink)
TABLE-US-00003 Slurry of fine aluminum grains obtained from an
aluminum 30 parts thin film (non-volatile content: 10%) Binder
resin: vinyl chloride containing carboxylic acid -vinyl 3 parts
acetate resin ("VINYLITE VMCH" manufactured by Union Carbide
Corporation (UCC)) Urethane resin 8 parts
("POLYURETHANE 2593" manufactured by Arakawa Chemical Industries,
Ltd. nonvolatile content: 32%)
TABLE-US-00004 Ethyl acetate 23 parts Methyl ethyl ketone 26 parts
Isopropanol 10 parts
The above materials were mixed to prepare an ink B-1 in which the
concentration of fine aluminum grains included in non-volatile
content was 35% by mass.
(5) Adhesive
(Preparation Example of Adhesive)
A two liquid type adhesive D-1 comprising 100 parts of an aromatic
polyether urethane resin (DICDRY AS-106A, manufactured by Dainippon
Ink and Chemicals, Incorporated, and "DICDRY" is a registered trade
name of this company) as a main component and 10 parts of an epoxy
(LR-100, manufactured by Dainippon Ink and Chemicals, Incorporated)
as a curing agent was obtained.
A rubber modified PMMA film (hereinafter, referred to as a film A),
which was transparent and had a surface luster value of 150
(60.degree./60.degree.) and a thickness of 100 .mu.m, was used as a
thermoplastic acrylic resin film, and an ABS film (hereinafter,
referred to as a film C), which was opaque and had a thickness of
300 .mu.m and color of gray, was used as a substrate layer.
Examples 1 to 8, Comparative Example 1
The layer constitution was provided as film A/intermediate
layer/ink B-1/adhesive D-1/film C. An intermediate layer was
provided by applying a solution, which was blended and mixed at a
ratio shown in Table 1, on a film A by using a microgravure coater
so that a dried film thickness thereof became 2.0 .mu.m and then
aging it at 40.degree. C. for 3 days. Subsequently, ink B-1 was
applied using a gravure coater thereon and dried to have a dried
film thickness of 2.0 .mu.m. Adhesive D-1 was coated thereon to
have a coating weight of 5.0 g/m.sup.2 using a gravure coater, and
it immediately adhered to the film C, and the resultant laminated
sheet for molding was aged at 40.degree. C. for 3 days. Then, the
laminated sheet for molding was mold-processed with a vacuum
molding method.
The reaction rate of the intermediate layer was determined by using
an infrared spectrophotometer after the solution blended and mixed
at a ratio shown in Table 1 was coated onto film A to have a dry
film thickness of 2.0 .mu.m and then aged at 40.degree. C. for 3
days.
The mold-processing was conducted by using a vacuum molding method
under conditions of sheet temperature of 155.degree. C. and metal
die temperature of 60 to 80.degree. C. wherein a test metal die
having a trapezoidal shape was used. The test metal die had a
square top surface having 5 cm sides, a bottom square surface
having 7 cm sides, and side surfaces having 2 cm sides; and the
sheet holding position was changed so that the sheets provided on
the square top surface were stretched to 130%, 150% and 200%
stretched (increase) size.
TABLE-US-00005 TABLE 1 T.sub.g of O Ethyl O (.degree. C.) N N/O
Ratio acetate Example 1 (O-1) 95 (N-1) 0.3 200 100 11.8 Example 2
(O-1) 95 (N-1) 0.5 200 100 19.7 Example 3 (O-1) 95 (N-2) 0.5 200
100 21.9 Example 4 (O-2) 72 (N-1) 0.5 200 100 18.0 Example 5 (O-1)
95 (N-1) 0.8 200 100 31.5 Example 6 (O-1) 95 (N-1) 1.0 200 100 39.4
Example 7 (O-3) 55 (N-1) 0.5 200 100 17.0 Example 8 (O-1) 95 (N-1)
0.05 200 100 2.0 Comparative Example 1 (O-1) 95 (none) 0.0 200 100
The meanings of the abbreviations in Table 1 are shown below. O:
acrylic resin having hydroxyl groups N: polyisocyanate N/O ratio:
molar ratio of functional groups of polyisocyanate compound to
those of acrylic resin having hydroxyl groups.
TABLE-US-00006 TABLE 2 Example 1 Example 2 Example 3 Example 4
Reaction rate (%) 78 73 73 70 Luster before molding 290 300 310 330
After 130% Luster 250 270 280 290 stretch Change 14% 10% 10% 12%
molding rate Cracking .largecircle. .largecircle. .largecircle.
.largecircle. After 150% Luster 230 260 270 275 stretch Change 21%
13% 13% 17% molding rate Cracking .largecircle. .largecircle.
.largecircle. .largecircle. After 200% Luster 220 250 255 260
stretch Change 24% 17% 18% 21% molding rate Cracking .largecircle.
.largecircle. .largecircle. .largecircle.
TABLE-US-00007 TABLE 3 Comparative Example 5 Example 6 Example 7
Example 8 Example 1 Reaction rate (%) 65 60 72 80 -- Luster before
molding 380 400 350 200 150 After 130% stretch Luster 340 365 320
165 110 molding Change 10% 9% 9% 17% 27% rate Cracking
.largecircle. .largecircle. .largecircle. .largecircle. .largeci-
rcle. After 150% stretch Luster 330 350 310 150 95 molding Change
13% 12% 11% 25% 37% rate Cracking .largecircle. .DELTA. .DELTA.
.largecircle. .largecircle. After 200% stretch Luster 320 345 300
140 80 molding Change 15% 14% 14% 30% 47% rate Cracking .DELTA.
.DELTA. .DELTA. .largecircle. .largecircle.
Examples 9 to 12
The layer constitution was provided as film A/intermediate
layer/ink B-1/adhesive D-1/film C. Laminated sheets for molding
were obtained similarly to in Example 1 except that an intermediate
layer was applied by using a micro-gravure coater with a solution,
which was blended and mixed at the ratio described in Example 2, to
have a dried thickness shown in following Table 2. Subsequently,
the same molding processing as example 1 was conducted by using a
vacuum molding process.
TABLE-US-00008 TABLE 4 Film thickness Luster 200% Stretch of
intermediate before Change layer (.mu.m) molding Luster rate (%)
Cracking Example 9 0.5 250 190 24 .largecircle. Example 10 4.0 340
300 12 .largecircle. Example 11 0.05 200 160 20 .largecircle.
Example 12 10.0 350 320 9 .DELTA.
INDUSTRIAL APPLICABILITY
The laminated sheet for molding of the present invention has an
initial good mirror-like metallic luster, stretching ability
necessary for molding such as in a vacuum molding process and the
like, and can maintain a good mirror-like metallic luster with
little reduction of luster.
More specifically, the present invention can provide a laminated
sheet for molding which has a good initial mirror-like metallic
luster, and stretching ability necessary in molding, specifically
the sheet has crack resistance against stretching conducted in a
thermal vacuum molding process, and the laminated sheet can provide
excellent design having a good mirror-like metallic luster even
after molding and can provide sufficient surface hardness without a
post-curing process.
* * * * *